Calculating accuracy for cross validation
I guess you could train your model with 10 different folds and in each fold calculate the average accuracy. So you would have 10 values - one corresponding to each fold. And then take the mean of all of them to get the average accuracy of your model.

Your first option doesn't seem great because you take the highest accuracy among folds. If for some reason, the variance between accuracies is high for a fold, this would bias your numbers. Taking mean or maybe median of accuracies might be more reasonable.

Does that help?